Telephone-exchange system



A. C. POWELL TELEPHONE EXCHANGE SYSTEM March 16 1926.

Filed Dec. 3, 1923 14 Sheets-Sheet 1 S QS I w if j@ .L %h.\ QS IW l@ www l..

A. C. POWELL TELEPHNE EXCHANGE SYSTEM March 16 1926. 1,577,076

Filed neo. s. 1923 14 `sheets-sheet 2 Mmh l16 192s. 1,577,076

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TELEPHONE EXCHANGE SYSTEM Filed s, 1923 ts-Sheet lq March 16,1926. 1,511,016

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A. c. PowELL TELEPHQNE EXCHANGE SYSTEM ava 14 She 'cs-Sheet 8 AAAAAA //7 ven/0f". 'fl/e/f d Powe# March 16 1926.

TELEPHONE EXCHANGE SYS TEM Fi Dec. 5

March 16 1926.

A. C. POWELL TELEPHONE EXCHANGE SYSTEM *cs-Sheet 10 V March 16, 1926. V.

1,577,076 A. c. POWELL TELEPHONE EXCHANGE SYSTEM Filed DeC- 5, 1923 14 Sheets-Sheet 11 y @UMA IMmh 16 1926.

1,577,076 l A. c. POWELL TELEPHONE EXCHANGE SYSTEM Filed Deo. 3, 1925 14 Sheets-Sheet l2 Affy March 16 1926.

. A. c. POWELL TELEPHONE EXCHANGE SYSTEM Filed Dec. 3, 1923 /.5 N

14 Sheets-Sheet 15 A March 16 1926.

1,577,076 A. c. PQWELL TELEPHONE EXCHANGE sYsTEM Filed Deo. s. 192s 14'sheets-sheet 14 Patented Mar. 16, 1926.

Unire srarss PATET QFFlQE.

ALBERT C. POWELL, 0F 'NEW YORIQN. Y., ASSIGNOR T0 WESTERN ELECTRIC O1VI PANY, INCORPORATED, OF NEW YORK, N. Y.,

A CORORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed` December 3, 1923. Serial No. 678,141.

To all whom t 'may concern:

Be it known that-l, ALBERT C, POWELL. a citizen ot the United States otl America', residing at New York, in the county ot' Bronx and State ot New York, have invented certain new and usetul improvements in Telephone-Exchange Systems, ot which the following is a full, clear, cencise, and exact description.

This invention relates to telephone exchange systems, and particularly to those systems wherein mechanical switching apparatus is employed in the establishmentof talking connections. .n

In switching areas including both manual offices and automatic oliices, where provision is made for the extension of calls made in an automatic otlice to any ot the outlying otlices either of the manual or automatic type, it is customary to cause the number ot a wanted rline terminating in a manual office to be displayed before the operator of such oflice by means ol a call indicator which is controlled from an oliice sender in the calling automatic otlice. operator noting the displayed number then completes the call by inserting the plug in which the trunk incoming trom the calling automatic office terminates in the :lack et the wanted line.

In such an exchange area it is desirable to permit incoming toll calls to be extended to either manual or automatic ollices and terminated therein by employing the same Y,

equipment in the terminating ollice as employed on intra-exchange calls. The cempletion ot such toll calls may be accomplished in much the same manner as intraexchange calls are established between' a calling manual oliice and either an automatic or manual terminating oi'ce by thc employment ot key indicator mechanism at the toll switching oice of the exchange.

H the wanted line terminates in an auto-- matic otilce ot the exchange 'thetoll operator may then employ key indicator metrianism ot' substantially the same type a. disclosedv in the Patent No. 1,513,362-, issued to L. 'M. Allen, October Q8, 1921i, forl selecting an idle trunk extending to the desired office and tor setting the automatic switches of such oilice to select the wanted line.

It, however, the wanted line terminates in a manual oflice, then provision mustbe made at the toll olhce for controlling-thecall indicator equipment at the desired inanual office to indicate to the operator the number ofthe line desired. rlhis is accomplished in accordance with the present invention by providing additional key indicator equipment at the toll otiice which functions not only to select an idle trunk extending to the desired manual otlice, but also functions under the control oit a toll operator to control the operation ot call indicator equipment at the manual oitlce.

At the toll office there are therefore provided a plurality of toll operators positions, each ot which has access to a plurality ot groups of outgoing trunks, one group extending to each of the distant manual offices served. Each position is further equipped with a senderv controlling keyboard, a set of oce keys and a set oi indicating lamps for trunk identification. rlhere are also located at the toll otlice a group ot Yregister senders common to the use of the operators and serying to transmit wanted line designations tor resti-stration upon call indicators in dist-ant manual ollices. In order that an idle sender may be taken for use to extend a call and to associate such sender with the keyboard at tlie opeiators position concerned, and also with an idle trunk in theparticular group leading tothe wanted manual otlice, a plurality of switching` units is employed. These units comprise three distinct parts, a sender selector for selecting an idle sender, trunk selectors for choosing an idle outgoing trunk, and a plurality oit operators position selectors. lllhen one ot the operators wishes to extend a call., an allotted'y ne ot' these switching units is set in motion, the three dilerent types ot switches comprising the units, all acting simultaneously. Y

The object ot the invention is therefore the provision in a system of the character outlined, ot means for enabling operators to control the extension orn calls to manual olices oi an exchange area equipped with call indicator mechanism, through the employment ot the regular equipment et the terminating manual otlices.

A feature oi the invention is the provision of a sender tor association with a switching unit of a calling manual otiice,

which is arranged to register the designaioo et tlie time nssocinted with tlie switching unit, und to transmit codes ot impulses oi' the proper character over tlie trunk circuit Selected by tlie switeliing unit for Causing t-lie registration ot the wanted line designntion upon n cull indicator in. the o'tliee in Wliicli the wanted line terininntes.

A further tintnre of tlie invention is tl'ie provision oi n tiining circuit eoini'non lo :i plurziliti7 ot switching units ior counting oil :i time interval, following the taking ot' :i unit into use by :in operator, sind in tlie event tlint :i su'iteliing unit doen not; tuno tion eonipleteliY within n presieribed period i'or operating :in zilnrin. filore particularly, this ienture relates to the provienen et menne tor testing tlie timing lende` extendingl from tlie eoniinon timing circuit to tlie eerernl un for detecting eueli conditions on the tinii. g lendel :is would pre 'ent die eorreet functioning ol. tlie tiining eirrnit u'itli relation to the switelii unito.

ltlier end turtlier i'eaiturer, eontelnplnted in the preeent inrention 'will lie olrrioun` l'roin n` eo .i

eiderntion ot the deeeription giron liereine'tter und also t'roin tlie uppended elninis.

Referring to the drnwinge, Figs. l to li, when teiten in tlie order Shown in Fig. .1.5, dieelose so inueli ot u telephone system ein bodying the principles of this inrention ns ie neeesenry to a comprehensive umlerritrnuling thereof.

Fig. l sliows one of o plurality ot' toll operzitors positions in n toll snitehing ot'- liee ot the exchange, provided with cord circuits t'or extending incoming toll culle over interotliee trunlos outgoing to tlie dietnnt innininl oiliees. One of these trunk1 is also illuetrnted in this figure. In uddition u. toll. district. selector is also shown :is inning :recess to the trunk circuit, tliifs toll district being under tlie direct control ot :i distnnt toll point.

Figs. I3, el und 5 show tile switches wliieli constitute one o't :i plurnlitir ot su'iteliing unite. Figs. und illiietrnte two ot :i Series of trunl Selector switcliee` for seleeting idle trunks outgoing to n pzirtieulr-.r infininil otiiee. lfig. t elio n eender Selector en'iteli lniriiig ec :u to :i group oi eonnnon register rendere. Fig. 5 Shows nn operatore position selecting ineclninisni which coneiete oi :i plurnliti7 ot seperate. po-

sitioii Selector switches, tiro oit tliese Switches bei shown in detail.

To the i'. t ot the right-houd broken line in Fig. t3, there eliown :in operntors position provided with ollire keine sind e series; of sender control keys. lilerween tlie tiro rertienl broken lines :inotlier operaitor`s position belonging to the sanne group ot positione :1S the one sl'iou'n. ui tlie right ot die ligure iel oleo selienioxieully illnstinted. To tlie extreine lett ot this; iigure is shown n tliird operntors position which is position No. l olf tlie fifth group. Fig. T shows n eet ot' indicating lamps located nt tlie o1'i .\.le,toi."e1 position illustrated et tlie riglit in Fig. t5, the function ot which is to gire the operator n. visual identitiention oi tlie selected trunks at lier position. Fig. S shows: :i storting end nn nllotting mechenisin coininon to tlie entire group of Switching units individuel to tlie group ot' trunks outgoing to the inzinuiil oil'iee illustrated.

liigs. t), lt), ll und 1;3 Show one ot n plu rnlitjrY of register senders located in the toll ottico und eonnnon to :ill operators posi* tiene: :tor controlling the setting ot' cull in dientors in tlie distant ninnuol otiiees. Figs. 5l und lll, teilten together. Show :i register eoiitrol Switch, sind its` :isnoeizited circuito. Fig. l() nino ,in tlie right portion tliereo'l F-'l o cnil iiulientor impulse ewiteli tor `iinsniitting eoll indicator code iinpulses. 5;. ll. und l2 elioiv fiets ot relaiT regieters upon which the designations of culled lines nre recorded. Fig. 13 shows n tiniing cir enit eoniinon to :i plurnlity ot switching units for operating nii nlnrin in the event tlint. n nwiteliing unit foils to function properly within :i predeterinined period, together with testing circuits for testing the timing lende extending t'roni tlie eoninion timing circuit to the .eerernl :nritelling unite` to wliieli it is' eonnnon.

Fig. lflr-iliows tlie incoming end ot the trunk circuit illustrated in Fig. l, terminan ing :itv n innnunl operatorie4 position iii uy niununl oiiiee ot :in exchange, together with n relay enll indicator illuntreted in 'the broken line reetnngle in the lower portion ot the figure. rit. the riglit of tlie ligure a.

line oit n eulnseriliei: terniinziting in the inanunl otlice is disclosed.

(Yew/wl denari/)Holi of' ripper/ffm um] operation.

The trunk Selector switches und P100, tlie sender selector eid), tlie position Sele@ tors i) und 510, tlie nllotter switch S00, und the register Control :Switch 10U() elioivn in Fig. it), :ire all ol tl'ie rotary single inotion stepliy-etep tliipe driven by stepping nirfiunets troni terininnl to terniinnl und so nriniiged tlint the ln'uiili'es :ire nioved torwzird to tlie next. terininiil upon deenergizntion of the stepping ningnet.

In ille system disclosed, connections nre estfdilielied by tlie operator in the manual toll otliee to any of e plurality of dietniit iniuiuel oiiiees. For euch manuel oiiiee to nliieli the operators` in tlie toll otliee lieve eccessi there provided :i group ol. inter eonnecting trunk lines terminating at the ninnunl otiice in culling plugs. At the toll olliee these trunks are inultipled So as to appear in jocks before each of the operators positions. The operator responds to an incoming toll call in the usual manner and upon ascertaining the name of the wanted otlice and the number of the wanted line therein, she manipulates the necessary apparatus at her position which causes the automatic selection ot' an idle trunk outgoing to such oliice; the association of an idle register sender with her position and with the selected trunk, andthe visual indication on indicator lamps of the identity of the select.- ed trunk. She then sets up the number of the wanted line on a keyboard at her position and completes the connectionv by inserting the calling plug of her cord circuit into the jack ot' the indicated outgoing trunk. The manipulation of the operators keyboard causes the desired designation io be registered upon the registers of the associated sender which thereafter serve to control the call indicator in the distant manual otlice to indicate the number of the wanted subscribers line.

As above noted, there is a group of out- `going trunks from the toll oflice to each of the distant manual otlices served. Only one ot these distantl ottices 1450 illustrated yin Fig. 14 of the drawing, and one of the trunksY 117, 115% leading theretohave been shown herein. For the group of trunks leading to the manual oliice there is provided in the 'toll ofhce a plurality of switching units, only one of which is shown in Figs. k2, 3, 4 and 5. While these switching units are individual to a single group of trunks outgoing to a single distant oflice, they are common to all register senders and are also common to all operators positions in the toll'oltice. Each or these switching units comprises a series of trunk selector switches, two of which are shown at 300 and 200, respectively.

Assuming that the group of trunks outgoing to the office in Fig. 14 is made up of 160 trunks, there will be provided in that case eight trunk selecting switches each having` a capacity of twenty trunks. The switch 300 serves the first twenty trunks in the group, the switch 200 serves the second twentytrunks, and so on for the remaining six selector switches.` 300 comprises a stepping magnet 301 and a plurality of brushes 302,303, 304, 305, 300 and 307, and their cooperating terminal banks. Similarly, the switch 200 consists oit a stopping magnet 201 and brushesl 202, 203, 204, 205, 206 and 207, and the corresponding terminal banks. .The same is true ot Vthe succeeding selector switches-not shown. The terminal banks with which the brushes 306 and 307 vof the selector switch 300 coopera-te, and the banks with which brushes 20G and 207 of switch 200 cooperate, and the corresponding` banks of all succeeding switches in the series have their terminals multipled, as illustrated, for a purpose he switch.

which will become obvious tromV the following description. Common to the entire series ot' trunk selector switches there is provided a steering or side switch 210 consisting ot stepping magnet 221, brushes 222, 22S, 224, 225, 226, and 227 and their cooperating terminal blanks. The purpose cf the side switch 210 is to determine the first one of the series of trunk selectors to be taken Jfor use and to govern the circuit changes during the transition from one selector switch izo the next. Provided all trunk selectors are in their-normal positions when a switching unit is taken for use, the lirst one of the switches in the series, namely the switch 300, will beset in motion to hunt 'for an idle trunk in the first group ot' twenty. It all thesev trunks are busy the switch 300, having moved its brushes completely over their bank terminals, causes the advance of the side switch 210 to its next position where the second trunk selector in the series is then effective and operates to search ttor an idle trunk in the second group of twenty. This procedure continues until an idle trunk is `inally found. The side switch 210 has no normal position but remains in the position corresponding to the trunk selector switch last taken for use so that when the unit is next operated, .that particular selector switch in the series is set in motion to search for an idle trunk instead ocommencing again at the beginning of the series.

In addition to the trunk selector switches, the switching unit also consists of a sencer selector switch 400 comprising a stepping magnet 401, brushes 402, 403, 404, 405, 405 and 407 and their corresponding terminal banks. Y

Lastly, the switching unit includes, to-

gether with the trunk selectors and the sent-.-` er selectors, a plurality of operators posi-- tion selector switches, two of which are shown at 500 and510. The switch 500 coinprises astepping magnet 507, brushes 501, 502, 5023,v 504, 505 .and 506 and their corresponding terminal banks, while the switch 510 similarly consists of a stepping magnet 517 together with brushes 511, 512, 518, Y514, 515 and 516. ln order to secure a better understanding of the purpose for dividing` the position selecting mechanism up into a plurality of selector switches, each separate and distinct from the other, an explanation will first be given of the plan on which the operators positions are grouped and divided.

Assume that the toll ollice has one hundred operators positions, which is a greater number than a single position selector swit h of the usual type can serve with the requisite speed and efficiency. Accordingly, the total number of one hundred operators positions is divided into live different groups oftwenty positions each, and

:zich ot the switching; units prtwided with tive position seleetor switches each having a capacity tor 'twenty operators? positions. The iiiosition selector 5th). for example, -serves the tiret group ot tu'eiity operators punitions in the otlice. The .first and seeond oi these positions in the tirst group et tifcnty are illustrated at t300 and (Slt). The next three suc cedingl position selector switches, which are not shown in the drawing?. serve the nent three `rroups of twenty operators positions. Finally, the last or itth position selector switch iii() serves the tlth group oi. twenty oiierators" positions, the first position oil which is schematically shown at (32d ot liii'. (i. The il'unction of the position selector switch 5th) oit the switchingt unit shown is to ssociate any one of the twenty positions with the register sender selected li the switch #lilo of the saine unit and to a I'iate the trunk indicating' meehu ni in Fien T at the, operatoi"s position witi the controlling devices pertaining to the truuk selecting switches of the same unit. and which are shown in Fie'. l. Likewise. this; the 'Function oi the remaining 'tour position selector switches of this switching unit with respect to the succeeding' Your groups ot' twenty operators` posilions.

,lince thertI are a iiilurality olf switching! units ix'idiridual to sich outgoing; group of trunks` there are., not shown, a nulnlier oi suitchinpn units etpiivalent and identical to the one shown in Figs. 2, 5l. Mil and o. The truuk selector switches, similar to Btl() and .tltl et each of these remaining,T units, have access to the saine outgoinglr trunks; the sender selectors, similar to switch 400, have access to the same common senders, and the ,ioaition selector switches 500, 510, etc., all have access to the saine corresponding groups of operators" positions. Vv'liere these .finiti hing); units are all equivalent to one another and may he taken for use by any one ot the operators in the exchange, an allottine device is employed lor allottiiug an idle switching unit for the use of any operator and tor preventing` more than one switching unit being taken 'ior use at the sume time. The allotter iior this purpose is shown in the :torni oil" the switch SOO in Fig. S. Svitch S00 consists of a stepping; maget 801, brushes 8 2, 803. Sil-i, 805, 80o and SOT and their corresponding terminal banks. The brush tltl'i' and its terminal bank pertain to the first position selector switch 500 of each of the several equivalent switching' units. The brush 809i and its terminal liank pertain to the filth or last position selector su'it h 51,0 ot each of the switching;r units. tliniilarly, the intermediate brushes G, S05 and 801 pertain, respectively, to the three intermediate position selectors oil each switching; unit belonging; to the outgoing Loi/'neve group ot' trunks leading.;l to the otllce Ilot).

The halai'lcinpr coi S152, together with the polarizedrelay 8111i-, acts to initiate the opiration of tl e allotted switching unit. under the control of any operator in the first `sjroup ot operators. r`he balancing` coil 8.13 and poiarized relay act to initiate the movement of the allotted switchingY unit under the control of any 0].iei'alor in the last or iitth group ol operators. Likewise, three intermediate balancing coils are provided (not shown), and serve, respectively, to .start the allotted switching units under the control oii operators in the three respective intermediate groups. The tive balancing coils are individual, respectivelyj to the .tive position selector switches ot each switchiniij unit.. For example, the coil S12 is indiidual to the position selector 500 liavingg access to the tirst group ot twenty operators positions. yihe coil 813 is individual to the lilith position selector switch 5l() havin-f access to the lilith group ot' twenty op erators positions. The saine is true of the remaining' balancingl coils and position selector switelles.

rThe register sender, shown in `Fios. 9, lil

1l und l2, comprises a ijilurality oif' groups oit registerinpy relays, a ,Qrou p .ior each digit to he recorded, which through the progressive operation oit' the switch 100() are placed under the control el the operator-s keyboard, and en impulse switch of the sequeine switch type which in accordance with Well known practice is arranged to send, during two revolutions thereof, series oi' impulses the character of which is determined by the several groups oi" register relays. These series of impulses are trans mitted to the manual termina-ting' oiliee for causing the call indicator therein to record the desired line designation.

Each of the Aseveral operators positions is equipped with a plurality of keys individual to the different outlying)- manual otlices to which connection may he extended from the toll oiiice. The keys G01, 621 and 62T ateach of the three positions shown in the drawing', are individual to the manual oilice litt). The manipulation el one of these keys hy the operator at the corresponding; position initiates the movement of the allotted switchini.;- unit individual to the `group of trunks outgoing' to that ofiice. For every' other ollice similar to the olliee 14h50, served through the toll otliee illustrated in this disclosure, there will he at each operators position an office key similar to thoseshown. The actuation of these keys will, in a similar manner, cause the movement of an al* lottetl sivittfliiine` unit7 similar to the one shown .in Figs. Q, 3, l and 5, but individual to the particular distant otliee represented h v the key depressed.

Two types of toll points are disclosed in loe Fig. 1, one shown in the upper left portion of the ligure comprising a tollswitching operators position providedV with a plurality of toll cords, only one being shown, and the associated key indicator mechanism shown in Figs. 2l to 13 inclusive. While this toll cord has been shown, for simplicity of disclosure, as having access directly to a calling line for answering calls initiated thereby, it would in practice be associated with the usual A and recording operators positions and calls incoming from toll points would be handled in accordance with standard toll practice.

The toll line switch 174 and the toll district selector 175, shown in the lower left portion of Fig. 1, are employed for establishing toll connections from other distant toll points and may be of the general type disclosed in the application of 1V. C. Jordon Serial No. 680,807, filed Dec. 15, 1923. Since the specific construction of these switches and the manner in which they are controlled by dial pulses from the distant toll points 'to select atrunk extending to the desired office of the exchanges are immaterial to an understanding of the invention, a detailed disclosure thereof is unnecessary herein.

The call indicator trunk shown in Fig. 14 and the call indicator associated therewith are of substantially the saine type as disclosed in the Patent No. 1,464,084, issued to A. E.-Lundell and E. H. Clark, August 7, 1923. The call indicator has been indicated diagrammatically in the small rectangle in the lower left portion of the ligure, and reference to the aforementioned patent may be'had for a full disclosure thereof.

Detailed Zcsc'frlpz'on of operation.

A general description having been given of the system and its purposes, a detailed eX- planation will now be made with respect to 'i the establishlnent of a telephone connection.

To this end it may be assumed that the subscribei1 of line 125 at a distant toll point desires to converse with the` subscriber of line 1475 in the manual o'liice 1450. The calling subscriber upon initiating a call becomes connected with the toll switching oiiice in the well known manner. The. operator ascertaining the number and oflice of the calling line and the'oflice and number of the de-v sired line over an orderA wire connection or in any well known manner, actuates the of- -in this circuit and close holding circuit ground.

for themselves as follows: battery through the contactof relay 613, right windings of relays 603 and 602, inner left contact of relay 602, inner back contact Vof relay`612, inner left front contact of relay 603 to The depression of key 601 also closes acircuit from battery, through the winding of relay 609, inner backA contact of relay 611, right Contact of key 601 to ground. Relay 609 operates and closes a circuit from battery through its winding and the winding` of relay 611 in series, front contact of relay 609, outer left contact of relay 603 to ground.

Relay 611, which is shunted as long as key 60l'is held actuated, operates in series with relay-609 over the circuit just traced at the instant. the operator releases the key 601. The operation of relay 603 closes a circuit from battery through the right VContact of said relay, back contact of relay 605, lamp 60?, outer back contact of relay 606 to ground. The lamp 607 lights and remains lighted` under the observance of the operator luntil an idle register sender has become associated ywith her position.

Immediately that relay 602 is energized a circuit is closed from battery through rcsistance 614,V outer contact of relay 612, outer left contact of lrelay 602, conductor 821-, thence to a point between the lowerwinding of the balancing coil 812 and the polarized relay 814. The iow of current to ground through the coil 812'and through the winding of the polarized relay 814 is in such a direction as to cause said relay to attract its armature. Relay 814 closes a circuit from battery through its contact, winding of relay 809, normal contacts of said relay, contact of relay 811 to ground.

Relay 809 operates and closes a locking circuit for itself through its inner left contact to ground. Relay 809, at its outer left contact, closes an energizing circuit for relay 811. Relay 811 attracts its armature and removes ground from conductor 823 thereby preventing the operation of another relay similar to relays 809 and 810 until the allotted switching unit hasI been started and another one allotted in its stead. Relay 809, on operating, closes `a circuit from ground through the contact of relayl 808, conductor 824,

right front contact of relay 809, brush 807, l

conductor 820, leading to the switching unit which isy allotted by the allotter switch 800l when standing in the position shown, winding of` relay 508 to battery. Relay 508V operates and closes a locking circuit for itself from battery throughv its winding and inner left contact to ground at the contact of rel ay 521. Relay 508 completes a circuit from ground through its outer right front contacts, conductor 535, right back Contact of relay 520, and thence in parallel through the winding of relay 519 to battery and over conductor 586 through the left Winding of 

